Summary of U.S. Geological Survey On-Line Instantaneous Fluvial Sediment Data
Glossary of Terms
The agency that is reporting the data. Agency codes are fixed values
assigned by the National Water Information System (NWIS).
The Federal Information Processing Standards (FIPS) code of the county or
county equivalent (parish, borough, etc.) in which the site is located.
The U.S. Geological Survey District office that operates the site.
The area enclosed by a topographic divide from which direct surface runoff
from precipitation normally drains by gravity into the stream above that
Hydrologic Unit Code (HUC)
Hydrologic units are geographic areas representing part or all of a surface
drainage basin or distinct hydrologic feature and are delineated on the
State Hydrologic Unit Maps. Each hydrologic unit is identified by a unique
number (HUC), and a name.
Data for water-quality samples, including suspended sediment,
bedload, and bed material, are stored under parameter codes. Each
parameter code defines a specific type of data. The USGS and USEPA typically
use similar parameter-code definitions, although there are exceptions to
this rule. Parameter codes fall into three classes:
Site and sampling-event data, such as site name, site ID, sample
Fixed-value codes, which are used to define a certain part of the process
of sample collection, processing, or quality assurance.
Chemical, physical, and biological data. The following illustrates how
codes are defined, and how for one type of measurement, several parameter
codes may exist.
Sediment, suspended, sieve diameter, percent finer
than 0.062 mm
Sediment, suspended, fall diameter, distilled
water, percent finer than 0.062 mm
Sediment, suspended concentration (mg/L)
Station Identification Number
Each site in the data base has a unique 8- to 15-digit identification number.